1. Field of the Invention
The present invention relates to a method of connecting a branch pipe to an existing main pipe, and more particularly to a method including the steps of: connecting and communicating a branch-pipe joint having a branching pipe portion to an existing main pipe; connecting a branch pipe to the branch-pipe joint; and communicating the branch pipe with the existing main pipe through the branch-pipe joint, with all these steps being effected while outflow of fluid from inside the main pipe being prevented.
2. Description of the Related Art
According to the method of connecting a branch pipe described above, the series of steps until the branch pipe and the existing main pipe becomes communicated with each other take place while preventing outflow of the fluid from the main pipe. Thus, in case the main pipe comprises a water pipe for example, the branch-pipe connecting operation may be effected without troubling the users with such inconvenience as suspension of water supply.
In the above method, as exemplified by the Japanese laid-open patent gazette Hei. 7-113489, a branch-pipe joint incorporating a sluice valve capable of opening/closing the branching pipe portion is connected and communicated with the existing main pipe while preventing fluid outflow therefrom. After the communication has been established between the branch-pipe joint and the main existing pipe, the sluice valve is operated to prevent outflow of the fluid, and then the branch pipe is connected with this sluice valve.
With the above-described conventional method, the method requires the branch-pipe joint having the sluice valve capable of opening/closing the branching pipe portion. Hence, the branch-pipe connecting operation is costly.
The present invention attends to the above-described drawback of the prior art and a primary object of the invention is to provide an improved method of connecting a branch pipe to an existing main pipe which method allows the branch-pipe connecting operation at lower cost through an ingenious modification of the conventional method.